ps2.h File Reference

PS/2 protocol interface. More...

#include <inttypes.h>

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Functions
void	ps2_init ()
	Init PS/2 related I/O and interrupts.
uint8_t	ps2_avail ()
	Check if the input buffer contains at least one byte.
uint8_t	ps2_getbyte ()
	Get one byte from input buffer. ps_avail() must be checked before doing so.
void	ps2_sendbyte (uint8_t)
	Transmit one byte and wait for completion.
uint8_t	ps2_busy ()
	Check if PS/2 statemachine is in IDLE state.
void	ps2_enable_recv (uint8_t)
	Suspend or enable PS/2 device by pulling clock line low.

---

Detailed Description

PS/2 protocol interface.

---

Function Documentation

uint8_t ps2_avail

(

)

Check if the input buffer contains at least one byte.

                    {
    return rx_head != rx_tail;
} 

uint8_t ps2_busy

(

)

Check if PS/2 statemachine is in IDLE state.

{ return state != IDLE; }

void ps2_enable_recv

(

uint8_t

)

Suspend or enable PS/2 device by pulling clock line low.

Parameters:

1

= enable

                                     {
    if (enable) {
        state = IDLE;
        ps2_dir(1,1);
        // enable INT0 interruptt
        GIFR |= _BV(INTF0);
        GICR |= _BV(INT0);
    } else {
        // disable INT0, then everything else
        GICR &= ~_BV(INT0);
        ps2_clk(0);
        ps2_dir(1,0);
    }
}

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uint8_t ps2_getbyte

(

)

Get one byte from input buffer. ps_avail() must be checked before doing so.

                      {
    uint8_t result = rx_buf[rx_tail];
    rx_tail = (rx_tail + 1) % PS2_RXBUF_LEN;
    
    return result;
}

void ps2_init

(

)

Init PS/2 related I/O and interrupts.

                {
    state = IDLE;
    rx_head = 0;
    rx_tail = 0;
    ps2_enable_recv(0);
    
    MCUCR |= _BV(ISC01); // falling edge for INT00
    TIMSK &= ~_BV(TOIE0);
}

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void ps2_sendbyte

(

uint8_t

)

Transmit one byte and wait for completion.

                                {
    while (state != IDLE);
     
    // 1. pull clk low for 100us
    ps2_enable_recv(0);

    tx_byte = byte;
    state = TX_REQ0;
    
    // 128us
    TCNT0 = 255-4; 
    TIMSK |= _BV(TOIE0);
    TCCR0 = 4;
    
    while (state != IDLE);
}

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